OLIMEX© 2017
A20-OLinuXino-LIME2 user's manual
2.4 Button functions
The bellow three buttons usually are supported under both Android and Debian:
PWR
– used to perform software turn off, software turn on; used to turn on board when powered by
battery – has to be held down for at least 5 seconds to perform each action
RESET
– used for hardware reset of the board
RECOVERY
– used to wake up the board from sleep
It is recommended to always make a soft “turn off” of the board. If that is not possible then please hold
PWR button down for a few seconds to “turn off the board”. Then you are free to remove the power
supply. If you disconnect the power supply (either the USB, the battery or the power jack) before turning
off the board you may corrupt your SD card. If you have placed NAND memory you can corrupt the
image on the NAND memory.
2.5 Interacting with the board
There are five typical ways to interact with A20-OLinuXino-LIME2. You can interact with A20-
OLinuXino-LIME2 and:
- a personal computer or another board via UART0 and a serial ow cable
- an HDMI monitor via the HDMI connector and an HDMI cable
- an LCD display via LCD_CON connector and 0.05'' step 40-pin cable
- a personal computer or another board via the mini USB connector and a mini USB cable, using SSH
protocol
- a personal computer via the Ethernet connector and a LAN cable, using SSH protocol
More details on each of the connections might be found in the consequent sub-chapters.
Note that not all interface options are available for all images. Furthermore, some of the ways of
interaction are (obviously) not suitable for Android OS. The official Debian image should give you the
most possible options of interfacing the board!
Using HDMI, LCD_CON or LAN might require additional configurations. Furthermore, it is possible to
corrupt the output settings over those interfaces and, thus, lose the output. In such cases, you can always
use the serial cable USB-SERIAL-CABLE-F as a reliable way to establish connection to the board.
2.5.1 Serial connection at UART0
The default and recommended way to communicate with the Linux operating system of the board is using
the serial connection available at UART0 connector. You would probably need an USB<->SERIAL cable
for such a connection. Even if you intend to use HDMI or LCD it is a good idea to have it as a basis – the
video output is not always reliable and if you set wrong display settings you would be unable to recover
the software without an alternative connection.
We distribute a ready-to-use cable. Even if you already have such a cable or you decide to purchase it
elsewhere it is advisable to check this product page for a reference:
Note that the levels at board's UART0 are in CMOS level (3.3V) and you would need a convertor to bring
them to the TTL level of your computer or cable! That is true for the RX and TX also! You would need to
consider that if you decide to make your own cable.
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